Low cost, low pollution and low viscosity fuel oil using heavy oil

ABSTRACT

A new type of fuel oil with low cost and low viscosity made of heavy oil or residue oil. The fuel oil is low cost, low viscosity and low pollution and includes base oil formed by adding waste plastic disposal oil made through thermal decomposition to heavy oil or residue oil of high viscosity, thereby decreasing the viscosity. The base oil is then provided with water and emulsifier to form water-in-oil emulsion fuel oil. The emulsifier is formed by mixing caustic soda (NaOH) and the calcium chloride (CaCl 2 ) and water. Substantial reduction in generation of pollutants in the exhaust gas is achieved when the fuel oil used in a combustion engine. The fuel oil is especially suitable for large and high power vessel engines.

FIELD OF THE INVENTION

[0001] This invention relates to a new type of fuel oil with low costand low viscosity made of heavy oil or residue oil, and moreparticularly, to low cost, low viscosity and low pollution fuel oilwhich includes base oil made by adding waste plastic disposal oil madethrough thermal decomposition to heavy oil or residue oil of highviscosity. The base oil is then provided with water and emulsifier toform water-in-oil emulsion fuel oil, thereby capable of reducinggeneration of pollutants in the exhaust gas when burnt in a combustionengine. The fuel oil of the present invention is especially suitable asvessel fuel oil.

BACKGROUND OF THE INVENTION

[0002] In a final stage of oil refining process, heavy oil is producedwhich is generally divided into three different classes, i.e., heavy oiltype A, heavy oil type B and heavy oil type C in accordance with theirviscosity. Since heavy oil generates high calory and is relativelyinexpensive, a large amount of heavy oil is consumed all over the worldfor facilities in various industries including large scale heatingfacilities and large vessels.

[0003] When heavy oil, in particular high viscosity heavy oil such asheavy oil C (superheavy oil) or low-grade residue oil, is burnt, a largevolume of pollutants, such as, sulphur oxides, nitrogen oxides, carbonmonoxide, soot and dust are generated. If no effective antipollutioncountermeasure is taken, these pollutants can contaminate theenvironment and pose a serious threat to the ecological system.

[0004] Accordingly, the governments of various countries havepromulgated various standards regarding the maximum permissibledischarge levels of toxic pollutants for facilities which burn heavyoil. The government imposes on the industries strict preventive measuresto keep the discharge level below the standard level. As a result, theindustries in which heavy oil is used as a fuel generally tend to makesubstantially large investments to equip heavy oil burning facilitieswith highly complex and expensive antipollution devices and facilities.

[0005] The superheavy oil, such as heavy oil C is required to add heatbefore being provided to burners or engines to lower the viscosity. Inrecent years, for high calories and economical reasons, heavier oil istend to be used for large engines such as vessel engines. Because it isnecessary to apply heat for adjusting the viscosity, the use of heavyoil involves increase in work load, equipment cost and operating cost(Journal of the Marine Engine Society in Japan, Vol. 34, No. 10, 1999,pp 647-649).

[0006] The inventors of this invention have disclosed engineperformances and exhaust gas properties of the oil made by adding wasteplastic disposal (WPD) oil to light oil and/or heavy oil. Based on thisexperience, the inventors have evaluated the oil made by adding the WPDoil to the heavy oil equivalent to the type C heavy oil, without addingheat, with respect to engine performances and exhaust gas properties. Asa result of this study, it is confirmed that the viscosity of such heavyoil is decreased because of the WPD oil added, thus the heavy oil C canbe used without applying heat. It is also confirmed that there issubstantially no adverse effects on the engine performances. Further,soluble organic fraction (SOF) and dry soot (DS) are significantlyreduced in the exhaust gas while involving a small degree of increase innitrogen oxides NO_(X) concentration (63TH Conference on MarineEngineering, 1999, pp 27-29).

[0007] It is known in the art that emulsified fuel oil is effective inreducing generation of soot when burnt in a burner such as a boilerbecause burning oil particles are further miniaturized bymicro-explosion of the water. Further, it is also known that, because itcontains water, burning temperature is lowered, resulting in reductionof the nitrogen oxides NO_(X).

[0008] The inventors of this invention have invented the heavy oilemulsifier for forming water-in-oil emulsion fuel oil using the heavyoil such as type C heavy oil or waste oil (Japanese Patent Laid-OpenPublication No. 11-5987). When used for land boilers, for example, thewater-in-oil fuel oil produced by the invention is effective insubstantially suppressing generation of contaminants such as soot,sulfur oxides, nitrogen oxides, carbon monoxides, and sulfide, which areordinarily contained in the exhaust gas of heavy or superheavy fuel oil.

[0009] According to this prior invention, the emulsifier mainly composedof caustic soda and calcium chloride promotes to produce thewater-in-oil emulsion by mixing the heavy oil and water. When theresultant water-in-oil fuel oil is combusted in a burner, thetemperature of the exhaust gas is lowered, thereby reducing thethermally caused nitrogen oxides NO_(X). Further, asphaltene (includingsulfur content) is neutralized by the added alkaline, thereby reducingsulfur oxides SO_(X). It was not quite clear, however, whether there isany difference between the combustion in a burner which is virtuallyunder ambient pressure and the combustion in an internal combustionengine which is under high pressure.

[0010] It was also unknown as to what influences the inorganic salt suchas sodium salt generated by the combustion will exert on the internalcombustion engine.

[0011] When burning the emulsion fuel oil, water contents react withunburnt carbon, and temporarily gasify to create carbon oxide andhydrogen, and then, gas-fire. Thus, when used in a boiler, for example,radiation of luminous flame caused by solid combustion of carbon tendsto be reduced. Further, it is known that because the emulsion fuel oilhas a higher water content ratio, radiation of non-luminous flame causedby the vapor is increased while radiation of luminous flame isdecreased, thereby offsetting with one another. However, it was unknownas to how the water content affects the performance of the internalcombustion engine.

[0012] Various reports have been made regarding the application ofemulsion fuel oil to diesel engines in cogeneration facilities and landfixed engines as well as to offshore tests for vessels. However, thereare many unknown factors, today, as to the combustion of the emulsionfuel oil in the internal combustion engine.

[0013] Air Pollution Law regulates exhaust gas produced by fixed onshorefacilities. Recently, in Japan, several new laws have been promulgatedwhich regulate soot and smoke in exhaust gas from vessels. Moreover, inSeptember 1997, IMO (International Marine Organization) has adoptedMARPOL Agreement Protocol IV, ratification of which is under preparationby each country. Thus, the regulation of the vessel exhaust gas will besoon to start.

[0014] Moreover, the regulation by IMO will be effective as of January,2001 and it is considered that the regulation will be retroactivelyapplied to vessels built after January, 2000. In principle, all vesselsare regulated, as to NO_(X), targets are limited to vessel dieselengines with greater than 130kW. In the regulation, with respect toSO_(X), the maximum content ratio of sulfur is limited to about 4.5%.With respect to NO_(X), different limits are provided depending onrotation speeds at rated output power level of the engines. For example,the maximum NO_(X) level is 17 g/kWh for a rotation speed less than 130rpm, the maximum NO_(X) level is 45×n(rpm)^(−0.2) g/kWh for a rotationspeed in the range of 130-2000 rpm, and the maximum NO_(X) level of 9.84g/kWh for a rotation speed higher than 2000 rpm.

[0015] Under the circumstances, there is an urgent need to reducenitrogen oxides NO_(X) in the exhaust gas from vessel engines. To meetthis requirements, as a practical measure available to reduce the NO_(X)in the exhaust gas of vessel engines, the use of emulsion fuel oil addedwith water is effective as a pretreatment process.

[0016] On the other hand, in Japan, Container and Package Recycle Lawhas been effective since 1997, for regulating various types of wasteplastic, which requires various recycling technologies. In this law,material recycles are limited to types of waste that can be collectedthrough specified routes, i.e., to vinyl chloride tubes recycled frompure waste vinyl chloride, fibers recycled from PET (polyesterterephthalate) bottles, and pure waste olefin. Since other types ofwaste plastic collected through regular routes include various mixtures,most widely used technology is a thermal recycle (rather than materialrecycle) in which the waste plastic is thermally decomposed to plasticoil or plastic gas.

[0017] It is expected that the recycle rates of the waste plastic willbe further increased. In such recycling processes, mixed plastic will berecycled in such ways that chlorine is recycled to hydrochloric acidthrough the thermal decomposition, PET bottles is recycled as phthalicacid, gasified components and carbonized refuse will be used as heatsource for thermal decomposition, and recycled oil components arerefined to be used as recycled oil.

[0018] At any rate, it is possible that the recycled plastic oil hasquality equivalent to light oil while the cost is lower than that of thelight oil. Therefore, effective use of the recycled plastic oil cancontribute to our environment in shifting to the resource circulatingsociety. Such an effective use of the recycled plastic oil also has animportant meaning to reduce an environmental load.

[0019] The inventors of this invention have been studying thecharacteristics of fuels made by mixing the heavy fuel oil with wasteplastic disposal (WPD) oil. The results of the study indicates that theviscosity of such heavy fuel oil is decreased because of the WPD oiladded thereto, which promotes easy handling. The results further showthat particulate matter such as soluble organic fraction (SOF) and drysoot (DS) are reduced while nitrogen oxides NO_(X) concentration isslightly increased.

[0020] Although different from the quality of the waste plastic, ingeneral, aromaticity in the decomposed oil increases, and thus, CCAI(Calculated Carbon Aromaticity Index) increases as well. Accordingly, acetane value decreases and an ignition lag increases which promotespremix, thereby reducing the generation of the particulate matter (DS,SOF).

[0021] Within the normal engine operation, when engine load increases,the ignition lag slightly decreases, while the maximum pressureincreases and exhaust gas temperature rises. Thus, although theparticles (DS, SOF) decreases, the nitrogen oxides NO_(X) concentrationincreases.

[0022] Various studies have been made with respect to methods ofreducing the NO_(X) concentration when using the emulsion fuel forengines. An example of such methods is to regulate the amounts ofpumping supply of the fuel and water in response to the engine load(Japanese Patent Laid-Open No. 8-303305). Another example shows a methodwhich has an emulsion fuel valve in a fuel supply line (Japanese PatentLaid-Open No. 11-159361). Further examples include a method ofcirculating the fuel (Japanese Patent Laid-Open No. 9-329067) and amethod of circulating the emulsion fuel (Japanese Patent Laid-Open No.8-246961).

[0023] Japanese Patent Laid-Open No. 9-317587 shows a method in which aninstrument for measuring NO_(X) is provided in an exhaust gas passagefor regulating the supply of heavy oil or water to reduce the NO_(X)concentration. This method has a disadvantage in that additional devicessuch as the measuring device and control valves have to be installed inthe engine, and such devices may be broken, resulting in engine trouble.Further, the emulsion fuel oil must be mixed before spraying in theengine, which further requires additional devices such as mixers andcontrollers.

[0024] To solve the environmental and natural resource problems,Japanese Patent Laid-Open No. 6-346071 discloses a method which formsemulsion fuel oil by adding water and a surface active agent to themixture of petroleum fluid oil and edible recycled oil to solveenvironmental problems. Further, Japanese Patent Laid-Open No. 7-11269shows a method which forms heavy oil emulsion fuel oil by adding waterand a surface active agent to the mixture of heavy oil and edible oil.However, it is unknown whether such emulsion fuel oil can be effectivelyused as engine fuels.

SUMMARY OF THE INVENTION

[0025] It is, therefore, an object of the present invention to providelow cost, low viscosity and low pollution fuel oil which includes baseoil made by adding waste plastic disposal oil made through thermaldecomposition to heavy oil or residue oil of high viscosity.

[0026] It is another object of the present invention to provide low costand low pollution fuel oil which can contribute thermal recycling ofwaste plastic disposal oil and heavy oil or residue oil of highviscosity without inversely affecting the environment.

[0027] It is a further object of the present invention to provide awater-in-oil emulsion fuel which is stable for a long period of time andis capable of reducing the emission of pollutants in the exhaust gas oflarge combustion engines such as used for vessels.

[0028] It is a further object of the present invention to provide amethod for producing a water-in-oil emulsion fuel product in whichdispersed phases of water are substantially uniformly distributed in adispersion medium of oil.

[0029] To achieve the above objectives, one aspect of the presentinvention is a water-in-oil emulsion fuel for a large size and highpower combustion engine. The emulsion fuel oil is comprised of base oilformed by mixing heavy oil and waste plastic disposal thermaldecomposition oil in a weight ratio from about 95:5 to about 80:20,thereby decreasing viscosity of the heavy oil without heating,emulsifier made of caustic soda (NaOH) and calcium chloride (CaCl₂), andwater added to the base oil in a weight ratio from about 5:95 to about20:80. The base oil, emulsifier and water are sufficiently mixed withone another so that the water substantially and uniformly distributed inthe base oil.

[0030] In the emulsion fuel of the present invention, the heavy oil isheavy oil type C or low grade residue oil having kinematic viscosity of500 centi-Stokes or higher at temperature 50° C. The waste plasticdisposal thermal decomposition oil is made through a thermaldecomposition process of olefin (polyethylene, polypropylene) orpolystyrene or a mixture of the olefin and polystyrene, and wherein whenthe waste plastic include vinyl chloride or vinylidene chloride, adechlorination process is preceded to the thermal decomposition processon the waste plastic. The waste plastic disposal thermal decompositionoil has kinematic viscosity of 5 centi-Stokes or lower at temperature30° C. is not solidify when left in air for a long period of time.

[0031] Preferably, a weight ratio of the emulsifier relative to thewater-in-oil emulsion fuel oil is in a range of 0.01-5 weight percent.Further preferably, the caustic soda (NaOH) and the calcium chloride(CaCl₂) in the emulsifier are about the same amounts with each other andmixed with water where a weight ratio of NaOH, CaCl₂ and water is about25:25:100.

[0032] Another aspect of the present invention is a method of producinga water-in-oil emulsion fuel. The method is comprised of the steps of:forming base oil by mixing heavy oil and waste plastic disposal thermaldecomposition oil in a weight ratio from about 95:5 to about 80:20,thereby decreasing viscosity of the heavy oil without heating, mixingcaustic soda (NaOH) and the calcium chloride (CaCl₂) and water to forman encapsulating emulsifier, adding the encapsulating emulsifier to amixture of the base oil and water wherein said mixture contains base oiland water in a weight ratio from about 95:5 to about 20:80; and mixingencapsulating emulsifier and the mixture of base oil and water so thatthe water substantially and uniformly distributed in the base oil.

[0033] The fuel oil of the present invention is produced by mixing theplastic oil made through thermal decomposition of waste plastic disposal(WPD) with heavy oil or residue oil of high viscosity to form base oil.The base oil is then mixed with water by using inorganic emulsifierincluding caustic soda (NaOH) and calcium chloride (CaCl₂), therebyforming water-in-oil emulsion fuel oil in which particles of water aredistributed and encapsulated in particles of oil each having apredetermined diameter. The water-in-oil emulsion fuel oil of thepresent invention improves the thermal efficiency of the engine withoutposing any problem and reduces generation of dust, SO_(X) or NO_(X) inthe exhaust gas.

[0034] In the present invention, since the emulsion fuel oil is made bymixing the low cost heavy oil or residue oil with the waste plasticdisposal (WPD) thermal decomposition oil, significant cost reduction canbe achieved. The water-in-oil emulsion fuel oil of the present inventioncontributes significant reduction of the particulate matters such asnitrogen oxides NO_(X), sulphur oxides SO_(X) and dry soot DS in theexhaust gas.

[0035] Further, in the present invention, instead of the surface activeagents used in the prior art technology, the emulsifier formed ofcaustic soda (NaOH) and calcium chloride (CaCl₂) are used which promotethe phase inversion at the oil surface for producing the water-in-oilemulsion fuel. The emulsion fuel is highly stable and remains unchangedfor a long period of time such as one month.

BRIEF DESCRIPTION OF THE DRAWINGS

[0036]FIG. 1 is a graph showing mixing ratios (vol %) of waste plasticthermal decomposition oil to heavy oil type C or residue oil in ahorizontal axis and density (g/cm³) of the mixture in a vertical axis.

[0037]FIG. 2 is a graph showing mixing ratios (vol %) of waste plasticthermal decomposition oil to heavy oil type C or residue oil in ahorizontal axis and sulfur content ratios (wt %) in the mixture in avertical axis.

[0038]FIG. 3 is a graph showing mixing ratios (vol %) of waste plasticthermal decomposition oil to heavy oil type C or residue oil in ahorizontal axis and kinematic viscosity (centi-Stokes) in the mixture ina vertical axis.

[0039]FIG. 4 is a graph showing molecular weight distribution of thewaste plastic thermal decomposition oil used in the experiment measuredby a gas chromatography analyzer.

[0040]FIG. 5 is a graph showing the molecular weight distribution of theheavy oil type C used in the experiment measured by the gaschromatography analyzer.

[0041]FIG. 6 is a graph showing the molecular weight distribution of themixture of the heavy oil type C and the waste plastic thermaldecomposition oil used in the experiment measured by the gaschromatograph analyzer.

[0042]FIG. 7 is a graph showing an engine performance where engine loadis shown in a horizontal axis while an ignition delay time is shown in avertical axis.

[0043]FIG. 8 is a graph showing an engine performance where engine loadis shown in a horizontal axis while exhaust gas temperature is shown ina vertical axis.

[0044]FIG. 9 is a graph showing an engine performance where engine loadis shown in a horizontal axis while concentration of DS (dry soot) inthe exhaust gas is shown in a vertical axis.

[0045]FIG. 10 is a graph showing an engine performance where engine loadis shown in a horizontal axis while concentration of nitrogen oxidesNO_(X) in the exhaust gas is shown in a vertical axis.

[0046]FIG. 11 is a graph showing an engine performance relative to awater content ratio in the emulsified fuel oil where the water contentratio (wt %) is shown in a horizontal axis while concentration ofnitrogen oxides NO_(X) in the exhaust gas is shown in a vertical axis.

[0047]FIG. 12 is a graph showing an engine performance relative to awater content ratio in the emulsified fuel oil where the water contentratio (wt %) is shown in a horizontal axis while concentration ofsulphur oxides SO_(X) in the exhaust gas is shown in a vertical axis.

[0048]FIG. 13 is a graph showing an engine performance relative to awater content ratio in the emulsified fuel oil where the water contentratio (wt %) is shown in a horizontal axis while concentration of DS(dry soot) in the exhaust gas is shown in a vertical axis.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0049] The fuel oil of the present invention make use of the superheavyoil with high viscosity, such as heavy oil C or low grade residue oil.An example of viscosity of such heavy oil is 500 centi-Stokes or more attemperature 50° C. As mentioned in the foregoing, the heavy oil must bereduced its viscosity by heating before being supplied to an engine.Because it is necessary to apply heat for adjusting the viscosity, theuse of heavy oil involves a relatively complicated heating system,resulting in increase in equipment cost and operating cost. Thereduction of viscosity can be achieved by mixing the heavy oil with lowviscosity oil such as heavy oil type A. However, it is considered thatsuch a method is not economically favorable today.

[0050] In the present invention, the viscosity of the heavy oil isreduced without applying the heat but by adding waste plastic oil. Suchplastic oil is made through thermal decomposition of waste plasticdisposal (WPD), i.e., recycled plastic. An example of temperature forsuch thermal decomposition is in the temperature range of 450-550° C. inwhich waste plastic disposal (WPD) is decomposed and is converted toplastic oil.

[0051] There are variety of ways to create the plastic oil. The onlyrequirement of the plastic oil suitable for the present invention isthat the waste plastic disposal is first dehydrochlorinated withrelatively low temperature such as 300° C. to remove the chloridetherefrom and then undergone the thermal decomposition process withtemperature such as 450° C. Further, the thermal decomposition plasticoil to be used in the present invention does not require any reformingor refining so long as it has a coefficient of kinematic viscosity ofless than 5 centi-Stokes at temperature 30° C. Such a degree ofviscosity in the plastic oil can sufficiently reduce the viscosity ofthe heavy oil.

[0052] Typically, the thermal decomposition plastic oil to be used inthe fuel oil of the present invention is made through thermaldecomposition of olefin (polyethylene, polypropylene) or polystyrene ora mixture of the olefin and polystyrene. When the waste plastic includevinyl chloride or vinylidene chloride, a dechlorination process shouldbe preceded to the thermal decomposition process of the plastic.

[0053] Since the thermal decomposition plastic oil is made from wasteplastic, it is difficult to maintain the quality of such oil within alimited range such as defined by the national standard JIS (JapaneseIndustrial Standard). Thus, the thermal decomposition plastic oil ofstandardized quality is not easily obtainable. Further, since theproduction scale of the thermal decomposition plastic oil is very small,it is not possible to reform and/or refine the plastic oil withefficient and economical ways.

[0054] Thus, at present, the thermal decomposition plastic oil is mainlyused as fuel oil for land boilers or as base material to mix with othermaterial. Because the thermal decomposition plastic oil is made bythermally decomposing the high molecular compound, it has relativelyhigh content ratios of benzene, toluene, xylene, and ethylbenzene.Accordingly, the thermal decomposition plastic fuel oil has a highcapability as solution, and thus, is most suitable for mixing with theheavy oil or residue oil.

[0055] Although such inorganic compound of benzene, toluene, xylene, andethylbenzene is suitable for solution, when used in an engine as a fuel,because the high level of CCAI (calculated Carbon Aromaticity Index), itincreases the ignition lag of the engine. Thus, when the engine load isincreased, the temperature of the exhaust gas is risen, resulting in theincrease in nitrogen oxides NO_(X) concentration in the exhaust gas.

[0056] One of the means for suppressing the generation of NO_(X) is toconvert the plastic oil to water emulsion. However, such water-in-oilemulsion requires to control the mixing ratio of water and oil dependingon the engine load. According to the study made by the inventors of thisinvention, if the water-in-oil emulsion of fixed mixing ratio is to beused without regard to the engine load, the emulsion must be highlystable and water particles must be equally and uniformly dispersedtherein.

[0057] The inventors of this invention have further studied thewater-in-oil emulsion with use of various types of surface activeagents. According to this study, it is found that, to uniformly dispersethe water particles, the amount of surface active agents or temperatureof the surface active agents must be carefully adjusted depending on thecomponents in the heavy oil and the thermal decomposition plastic oil.Further, a long time is required for mixing the heavy oil, plastic oil,water and surface active agents. Thus, the process using the surfaceactive agents involves the long time and complicated process.

[0058] To solve this problem, in the present invention, when mixing baseoil (mixture of heavy oil and thermal decomposition plastic oil) andwater, water solution mainly constituted of caustic soda (NaOH) andcalcium chloride (CaCl₂) is added to the base oil. Because of thissolution, at the early stage of forming the emulsion, ionized Na+ andOH⁻and water solution CaCl₂ become continuous phases, therebydistributing oil particles in the water and forming oil-in-wateremulsion. Thus, during the mixing process, fatty acid and the likecontained in the heavy oil and the thermal decomposition plastic oil aresaponified and oriented to the surface to act as surface active agentsso that calcium (Ca) gradually ionized and changed the free energy atthe surface to form the water-in-oil emulsion by phase inversion. Thewater-in-oil emulsion produced according to the present invention ishighly stable and water particles are equally and uniformly dispersedtherein.

[0059] According to the water-in-oil emulsion fuel oil of the presentinvention produced as above using the heavy oil and the thermaldecomposition plastic oil, there is no need to apply heat to lower theviscosity or to use any special facility to produce the emulsion. Theemulsion fuel oil of the present invention can be used in the existingengines without any adverse effects on the engine performances whileachieving substantial reduction in particulate matter such as SOF(soluble organic fraction) and DS (dry soot) as well as nitrogen oxidesNO_(X).

[0060] It is considered that such reduction of SOF and DS in the presentinvention is based on the following reasons. First, the viscosity of thebase oil (mixture of heavy oil and plastic oil) is low and thus diameterof the sprayed particles is small. Second, the distributed waterparticles rapidly expand and explode by the heat in the engine so thatthe oil particles are further miniaturized. Third, because of water gasreaction between high temperature vapor and carbon, the solid carbon inthe emulsion fuel oil is reduced, thereby shifting to gas-fire.

[0061] In particular, since the waste plastic oil includes a largeamount of ring inorganic compound, the inventors have initiallyconcerned about possible increase in SOF (soluble organic fraction) inthe exhaust gas. In reality, however, there was no increase in SOF,which is probably related to the water gas reaction noted above. It isconsidered that the reduction of NO_(X) is derived mainly from the factthat the emulsion fuel oil contains relatively large amount of waterwhich lowers the burning temperature.

[0062] With respect to the present invention, several experiments havebeen performed, the results of which are described in the following:

[0063] Experiment 1

[0064] The inventors have examined the characteristics of the base oilformed by mixing the heavy oil C listed in Table 1 or the low graderesidue oil listed in Table 2 with the waste plastic disposal (WPD)thermal decomposition oil listed in Table 3. FIGS. 1 and 2 show theresultant characteristics of the fuel oil of the present invention. Therate of WPD thermal decomposition oil added to the heavy oil C or theresidue oil was varied from 0, 10, 20, 30 to 40 vol % (volume percent)and the changes in density (FIG. 1) and the changes in sulfur contents(FIG. 2) were respectively examined. Such changes shown in FIGS. 1 and 2are normal changes derived from mixing the corresponding oils. TABLE 1Unit Value Density (15° C.) g/cm³ 0.982 Kinematic Viscosity (50° C.)mm²/s ( = cSt) 177 Carbon Residue wt % 12.3 Sulphur wt % 2.56 Ash wt %0.02 Nitrogen wt % 0.25 Higher Calorific Value kcal/kg 10,220

[0065] However, as shown in FIG. 3, the kinematic viscosity of the baseoil is significantly decreased especially between the mixing ratiosbetween 10 vol % and 20 vol %. The kinematic viscosity of the heavy oilC is decreased from about 180 centi-Stokes to about 15 centi-Stoke. Thekinematic viscosity of the low grade residue oil is decreased from about510 centi-Stokes to 30 centi-Stokes. The inventors consider that this isbecause the WPD thermal decomposition oil contains a large amount ofaromatic compound which has high affinity with asphaltene, and as such,the content ratio of the saturated components, asphaltene, aromaticcompound, and resin in the heavy oil or low grade residue oil, has beenchanged. TABLE 2 Unit Value Density (15° C.) g/cm³ 0.991 KinematicViscosity (50° C.) mm²/s ( = cSt) 510 Carbon Residue wt % 16.2 Sulphurwt % 3.18 Ash wt % 0.02 Nitrogen wt % 0.32 Higher Calorific Valuekcal/kg 10,100

[0066] FIGS. 4-6 show molecular weight in the base oil. The molecularweight is measured by a gas chromatography analyzer (GCM8-QP5000). FIG.4 shows the molecular weight of the WPD thermal decomposition oil, FIG.5 shows the molecular weight of the heavy oil C, and FIG. 6 showschanges in the molecular weight in the fuel oil made by adding the WPDthermal decomposition oil by 20 vol % to the heavy oil C. These drawingsshow that the components in the WPD thermal decomposition oil and theheavy oil C have been changed by mixing with one another. TABLE UnitValue Density (15° C.) g/cm³ 0.939 Kinematic Viscosity (30° C.) mm²/s (= cSt) 1.189 Styrene monomer wt % 63.9 Styrene dimer wt % 11.5 Styrenetrimer wt % 5.7 Toluene wt % 2.2 Ethyl Benzen wt % 1.4 Alpha MethylStyrene wt % 2.2 Other wt % 13.1

[0067] An engine performance involving the base oil made of the heavyoil C mixed with the WPD thermal decomposition oil (20 vol %) is shownin FIGS. 7-10. In FIG. 7, a horizontal axis is engine load and avertical axis is an ignition delay time. As can be seen in FIG. 7, whenthe engine load increases, the ignition delay time decreases. In FIG. 8,a horizontal axis is engine load and a vertical axis is an exhaust gastemperature. As can be seen in FIG. 8, when the engine load increases,the exhaust gas temperature rises.

[0068] In FIG. 9, a horizontal axis is engine load and a vertical axisis a concentration of DS (dry soot) in the exhaust gas. As can be seenin FIG. 9, when the engine load increases, the DS concentrationdecreases. In FIG. 10, a horizontal axis is engine load and a verticalaxis is a concentration of nitrogen oxides NO_(X) in the exhaust gas. Ascan be seen in FIG. 10, when the engine load increases, theconcentration of NO_(X) in the exhaust gas tends to increase. Within themixing ratios of 5-20 vol % of the WPD thermal decomposition oil in theheavy oil C, the engine can operate for all of the load. The dry soot(DS) concentration has been decreased with the increase of the loadwhile the nitrogen oxides NO_(X) concentration has been increased withthe increase of the load.

[0069] Experiment 2

[0070] Water was added to the base oil described with respect to theexperiment 1 above with mixing ratios of 0, 5, 10, 15, 20, 25 and 30(weight percent), respectively. The base oil mixed with the water wasfurther mixed with encapsulating emulsifier shown in Table 4 with amixing ratio of 0.1 (weight percent) relative to the sum of the base oiland the water, thereby forming the water-in-oil emulsion fuel oil. Thevalue in Table 4 is amounts of caustic soda (NaOH) and the calciumchloride (CaCl₂) with respect to water of 100 g. As shown in Table 4,the caustic soda (NaOH) and the calcium chloride (CaCl₂) in theencapsulating emulsifier are about the same amounts with each other andmixed with water where a weight ratio of NaOH, CaCl₂ and water is about25:25:100. The engine performance using the water-in-oil emulsion fueloil was examined while operating under 75% engine load. Theconcentration ratios of the dry soot (DS), the nitrogen oxides (NO_(X))and the sulfur oxides (SO_(X)) in the exhaust gas were measured. TABLE 4Unit Value Caustic soda (NaOH) g 25 Calcium chloride (CaCl₂) g 25

[0071] In this experiment, for the water mixing (content) ratio of 20 wt% (weight percent) or lower, the engine can operate under all of theengine load. For the water mixing ratio higher than 20 wt %, the engineperformance showed instability, requiring adjustments in the fuel. Forthe water mixing ratio higher than 25 wt %, continuous operation of theengine was no longer possible.

[0072]FIG. 11 shows the engine performance relative to the water contentratio in which the water content ratio (wt %) is shown in a horizontalaxis while the concentration of nitrogen oxides NO_(X) in the exhaustgas is shown in a vertical axis. As can be seen in FIG. 11, the NO_(X)concentration is decreased with the increase of the water. For example,the NO_(X) is reduced to half (½) when the water content ration is 20 wt%. In FIG. 12, the water content ratio (wt %) is shown in a horizontalaxis while concentration of sulphur oxides SO_(x) in the exhaust gas isshown in a vertical axis. As shown in FIG. 12, the SO_(X) concentrationis decreased with the increase of the water. For example, the SO_(X) isreduced to ⅔when the water content ratio is 20 wt %. In FIG. 13, thewater content ratio (wt %) is shown in a horizontal axis while theconcentration of DS (dry soot) in the exhaust gas is shown in a verticalaxis. As shown in FIG. 13, the DS concentration is decreased with theincrease of the water. For example, the DS is reduced to ¾when the watercontent ratio is 15 wt %.

[0073] Experiment 3

[0074] This experiment is to examine the optimum mixing ratios in thewater-in-oil emulsion fuel oil. Table 5 shows such optimum mixing ratiosof the base oil, water and emulsifier in accordance with the presentinvention. The water was added to the base oil described with respect tothe Experiment 1 above (the mixture of the heavy oil C with the WPDthermal decomposition oil or the mixture of the low grade residue oilwith the WPD thermal decomposition oil) with mixing ratio 20 wt %(weight percent). The base oil mixed with the water was further mixedwith encapsulating emulsion shown in Table 4. TABLE 5 Base Oil WaterEmulsifier Base Oil Component (vol %) (vol %) (wt %) Heavy Oil C + WPD95  5 0.01 20 vol % Heavy Oil C + WPD 90 10 0.03 20 vol % Heavy Oil C +WPD 85 15 0.06 20 vol % Heavy Oil C + WPD 80 20 0.10 20 vol % Heavy OilC + WPD 75 25 0.14 20vol% Heavy Oil C + WPD 70 30 0.18 20 vol % LowGrade Residue Oil + 95  5 0.50 WPD 20 vol % Low Grade Residue Oil + 9010 1.56 WPD 20 vol % Low Grade Residue Oil + 85 15 3.10 WPD 20 vol % LowGrade Residue Oil + 80 20 5.00 WPD 20 vol % Low Grade Residue Oil + 7525 7.25 WPD 20 vol % Low Grade Residue Oil + 70 30 9.83 WPD 20 vol %

[0075] As shown in Table 5, when the water mixing ratios between 5-20 wt% (weight percent) relative to the sum of the weight of the water andbase oil, the optimum ratio of the encapsulating emulsifier of Table 4is in the range between 0.01-5 wt % (weight percent). After one monthfrom forming the water-in-oil emulsion fuel oil in which water particlesare uniformly dispersed in the oil, the engine can operate without anyproblems.

[0076] Experiment 4

[0077] Other than the water-in-oil emulsion fuel oil prepared for theExperiment 3, water-in-oil emulsion fuel oil was produced by using anonionic surface active agent and an anionic surface active agentavailable in the market. A sum of both surface active agents with weightpercent of 1 wt % (0.5 wt % of each of the nonionic and anionic surfaceactive agents) is mixed with the base oil. After leaving the resultantemulsion fuel oil for predetermined days (storage periods), theperformance of the engine was examined using this emulsion fuel oil. Theresultant data of this experiment is shown in Table 6. TABLE 6 WaterStorage Engine Base Oil Component (vol %) (days) Operation Heavy Oil C +WPD 5 7 Normal 20 vol % Heavy Oil C + WPD 10 7 Impossible 20 vol % LowGrade Residue Oil + 5 10 Need WPD 20 vol % Adjustment Low Grade ResidueOil + 10 10 Impossible WPD 20 vol %

[0078] As to the emulsion fuel oil using the base oil including theheavy oil C, after seven days, the engine was not able to operate at anyload for the water content ratio of 10 vol %. Similarly, as to theemulsion fuel oil using the base oil including the low grade residue oilC, after ten days, the engine was not able to operate at any load forthe water content ratio of 10 vol %. Further, in the case of the baseoil using the low grade residue oil, various adjustments were necessaryeven when the water content ratio is 5 vol %. Especially, when the loadis light, it was necessary to proportionally control the flow rate ofthe fuel oil.

[0079] It is considered that the cause of such engine trouble in theforegoing is that the water is not uniformly dispersed in the oil. Suchlack of uniformity of the water was occurred during the storage periods.

[0080] As has been described above, the water-in-oil emulsion fuel oilproduced by the method of the present invention is stored in a fuel tankfor a long period of time and can be used for vessel engines without anychanges. The fuel oil of the present invention is effective in reducingthe toxic substances in the exhaust gas of the engine.

[0081] In the present invention, since the emulsion fuel oil is made bymixing the low cost heavy oil or residue oil with the waste plasticdisposal (WPD) thermal decomposition oil, significant cost reduction canbe achieved. The water-in-oil emulsion fuel oil of the present inventioncontributes significant reduction of the particulate matters such asnitrogen oxides NO_(X), sulphur oxides SO_(X) and dry soot DS in theexhaust gas.

[0082] Further, in the present invention, instead of the surface activeagents used in the prior art technology, the emulsifier formed ofcaustic soda (NaOH) and calcium chloride (CaCl₂) are used which promotethe phase inversion at the oil surface for producing the water-in-oilemulsion fuel. The emulsion fuel is highly stable and remains unchangedfor a long period of time such as one month. This method of producingthe water-in-oil emulsion can be easily conducted on a ship. It isexpected that low viscosity waste oil other than the WPD thermaldecomposition oil may also be used. Further, the method of producing thewater-in-oil emulsion fuel oil of the present invention can be used inocean going ships which use fuel oil of different qualities.

[0083] The presently disclosed embodiments are to be considered in allrespects as illustrative and not restrictive. The scope of the inventionbeing indicated by the appended claims, rather than the foregoingdescription, and all changes which come within the meaning and range ofequivalency of the claims are, therefore, intended to be embracedtherein.

What is claimed is:
 1. A water-in-oil emulsion fuel for a large size andhigh power combustion engine, comprising: base oil formed by mixingheavy oil and waste plastic disposal thermal decomposition oil in aweight ratio from about 95:5 to about 80:20, thereby decreasingviscosity of the heavy oil without heating; emulsifier made of causticsoda (NaOH) and calcium chloride (CaCl₂); and water added to the baseoil in a weight ratio from about 5:95 to about 20:80; wherein the baseoil, emulsifier and water are sufficiently mixed with one another sothat the water substantially and uniformly distributed in the base oil.2. A water-in-oil emulsion fuel as defined in claim 1, the heavy oil isheavy oil type C or low grade residue oil.
 3. A water-in-oil emulsionfuel as defined in claim 1, wherein the waste plastic disposal thermaldecomposition oil is made through a thermal decomposition process ofolefin (polyethylene, polypropylene) or polystyrene or a mixture of theolefin and polystyrene, and wherein when the waste plastic include vinylchloride or vinylidene chloride, a dechlorination process is preceded tothe thermal decomposition process on the waste plastic.
 4. Awater-in-oil emulsion fuel as defined in claim 1, wherein a weight ratioof the emulsifier relative to the water-in-oil emulsion fuel oil is in arange of 0.01-5 weight percent.
 5. A water-in-oil emulsion fuel asdefined in claim 1, wherein the caustic soda (NaOH) and the calciumchloride (CaCl₂) in the emulsifier are about the same amounts with eachother and mixed with water where a weight ratio of NaOH, CaCl₂ and wateris about 25:25:100.
 6. A water-in-oil emulsion fuel as defined in claim2, wherein the heavy oil or low grade residue oil has kinematicviscosity of 500 centi-Stokes or higher at temperature 50° C.
 7. Awater-in-oil emulsion fuel as defined in claim 3, wherein the wasteplastic disposal thermal decomposition oil has kinematic viscosity of 5centi-Stokes or lower at temperature 30° C. is not solidify when left inair for a long period of time.
 8. A method of producing a water-in-oilemulsion fuel, comprising the following steps of: forming base oil bymixing heavy oil and waste plastic disposal thermal decomposition oil ina weight ratio from about 95:5 to about 80:20, thereby decreasingviscosity of the heavy oil without heating; mixing caustic soda (NaOH)and the calcium chloride (CaCl₂) and water to form an encapsulatingemulsifier; adding the encapsulating emulsifier to a mixture of the baseoil and water wherein said mixture contains base oil and water in aweight ratio from about 95:5 to about 20:80; and mixing encapsulatingemulsifier and the mixture of base oil and water so that the watersubstantially and uniformly distributed in the base oil.
 9. A method ofproducing a water-in-oil emulsion fuel, as defined in claim 8, wherein aweight ratio of the emulsifier relative to the water-in-oil emulsionfuel oil is in a range of 0.01-5 weight percent.
 10. A method ofproducing a water-in-oil emulsion fuel as defined in claim 8, whereinthe caustic soda (NaOH) and the calcium chloride (CaCl₂) in theemulsifier are about the same amounts with each other and mixed withwater where a weight ratio of NaOH, CaCl₂ and water is about 25:25:100.